Immunogenicity of Beta-lactam antibiotics - penicillins and cephalosporins - is being investigated by in vitro analysis of rates and types of degradation under physiological conditions and at concentrations of antibiotics and reactive substrates likely to occur during therapy. Reactive products, including polymers, are identified by chromatographic separation. Improved methods of 3H-radio-labelling of Beta-lactam antibiotics by hydrogen-exchange are also being sought, based on knowledge of their chemical stability in aqueous solutions, and will be used to study by radioimmunoassay in vivo haptan substitution of autologous proteins and membranes. Chemotactic and chemokinetic responses of human polymorphonuclear leukocytes (PMNs) are being studied by radial migration beneath agarose to determine optimal conditions for assay of the lymphokine LIF. Formyl-peptide (FMLP) stimulated migration and its enhancement by a heat stable serum factor (which protects against peptide-induced PMN degradation) has been established as identical morphologically to chemotactic response. Further studies of responses of normal and abnormal human PMNs in this system and of the mode of LIF action are planned.